JP3968698B2 - Dehydration method for organic sludge with high fat content - Google Patents

Description

【００１３】
実施例１
４０％塩化第二鉄溶液０．３ｍｌを添加し、３０秒間攪拌し、次いでアニオン性有機高分子凝集剤Ａの０．１％水溶液７ｍｌを添加し、３０秒間攪拌し、次いで両性有機高分子凝集剤Ｂの０．２％水溶液１０ｍｌを添加し、３０秒間攪拌した。
【００１４】
実施例２
実施例１においてアニオン性有機高分子凝集剤Ａに代えて、アニオン性有機高分子凝集剤Ｃの０．１％水溶液７ｍｌを添加したことを除き、実施例１と同じ処理を行った。
【００１５】
比較例１
実施例１においてアニオン性高分子凝集剤Ａの添加ステップを省略したことを除き、実施例１と同じ処理を行った。
【００１６】
比較例２
実施例１において両性高分子凝固剤Ｂの添加ステップを省略したことを除き、実施例１と同じ処理を行った。
【００１７】
比較例３
両性高分子凝集剤Ｂの０．２％水溶液１０ｍｌを添加し、３０秒間攪拌した。
【００１８】
比較例４
４０％塩化第二鉄水溶液０．３ｍｌを添加し、３０秒間攪拌し、次いで両性有機高分子凝集剤Ｂの０．２％水溶液１０ｍｌを添加し、３０秒間攪拌し、次いでアニオン性有機高分子凝集剤Ａの０．１％水溶液７ｍｌを添加し、攪拌した。
【００１９】
実施例１−２および比較例１−４においてフロックの凝集状態（フロック径）およびその固液分離の容易さを評価した結果を表２に示す。
【００２０】
【表２】

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a technique for treating organic sludge generated mainly in food factories.
[0002]
[Prior art]
Conventionally, organic sludge is dehydrated by using a combination of a cationic organic polymer flocculant, or an inorganic flocculant such as vanous sulfate or ferric chloride and an amphoteric organic polymer flocculant. In general, a method of performing solidification and liquid separation using a dehydrator is performed.
[0003]
[Problems to be solved by the invention]
However, sludge containing a very large amount of fats and oils (for example, sludge from meat factories such as pigs) has poor agglomeration, and there are cases where these formulations cannot be treated satisfactorily. If sludge coagulation cannot be achieved satisfactorily, sludge coagulation and dehydration will occur due to problems such as heavy loads on the wastewater treatment process, such as activated sludge, and increased sludge dewatering cake volume and waste disposal costs. Processing needs to be done reliably.
[0004]
[Means for Solving the Problems]
As a result of intensive studies on the coagulation treatment method using such sludge that contains a large amount of oil and fat and difficult to dewater, the present inventors have conditioned the sludge so that it is likely to coagulate with an acidic inorganic coagulant. And an anionic organic polymer flocculant and an amphoteric organic polymer flocculant in order. The coagulated sludge is easily treated with a belt press type dehydrator or a centrifugal dehydrator that has been generally used.
[0005]
As described above, in the present invention, a flocculant is added to organic sludge containing fats and oils, and the flocs are separated and then dehydrated by a dehydrator. The present invention relates to a method for dewatering organic sludge, characterized by adding an acidic acidic inorganic flocculant, adding an anionic organic polymer flocculant second, and adding an amphoteric organic polymer flocculant third.
[0006]
The inorganic flocculant may be an agent generally used in water treatment, such as ferric chloride, polyiron sulfate, polyaluminum chloride, and vanous sulfate.
[0007]
As the anionic organic polymer flocculant, a copolymer of acrylamide-sodium acrylate is generally used. However, any anionic water-soluble polymer similar to this can be used.
[0008]
As the amphoteric organic polymer flocculant, an acid salt (or quaternized salt) of acrylamide-acrylic acid-dimethylaminoethyl (meth) acrylate is widely used, and it can be used. The molar ratio (CV / AV) between the cationic structural unit and the anionic structural unit in the amphoteric flocculant is preferably 1 or more. Moreover, 5-50 mol% of the cation structural unit is desirable.
[0009]
The order of drug addition is 1. Inorganic flocculant (adjusted to pH 4-6)
2. 2. Anionic organic polymer flocculant Add in the order of amphoteric organic polymer flocculants. If the order is changed, a satisfactory aggregation effect may not be obtained, and in the worst case, no aggregation occurs.
The amount of each flocculant added is about 0.05 to 1% by weight for the anionic organic polymer flocculant and about 0.1 to 2% by weight for the amphoteric organic polymer flocculant with respect to the solid content of the organic sludge. The iron-based or aluminum-based acidic inorganic flocculant is not particularly limited.
[0010]
Although the aggregation mechanism according to the method of the present invention is not fully understood, the following aggregation mechanism is conceivable.
1. The fat and oil are coagulated with the inorganic flocculant to form fine flocs with the fat and oil as the core, and the anionic organic polymer flocculant is easily adsorbed.
2. Adsorbs to the fine flocs produced by the anionic organic polymer flocculant. However, at this stage, the adsorptive power of the anionic organic polymer flocculant is weak, and the physical strength of the aggregate is very weak because oil and fat are the core, and no coarse floc is generated.
3. When an amphoteric organic polymer flocculant is added, it reacts with fine flocs having an oil and fat core and an anionic organic polymer flocculant to insolubilize and produce strong flocs.
[0011]
【Example】
Applicable sludge properties (sewage sludge from a meat factory)
(2.5% solids per solid: 40% fat, 39% protein, 5% mineral, 11% fiber)
200 ml of the test sludge was collected in a 300 ml beaker, and the coagulation test of Examples and Comparative Examples was performed. Agitation was set at a speed of 250 rpm with a jar tester. Table 1 shows the organic polymer flocculants used.
[0012]
[Table 1]

[0013]
Example 1
Add 0.3 ml of 40% ferric chloride solution and stir for 30 seconds, then add 7 ml of 0.1% aqueous solution of anionic organic polymer flocculant A, stir for 30 seconds, and then amphoteric organic polymer agglomeration 10 ml of 0.2% aqueous solution of Agent B was added and stirred for 30 seconds.
[0014]
Example 2
The same treatment as in Example 1 was performed except that 7 ml of a 0.1% aqueous solution of the anionic organic polymer flocculant C was added in place of the anionic organic polymer flocculant A in Example 1.
[0015]
Comparative Example 1
The same treatment as in Example 1 was performed except that the step of adding the anionic polymer flocculant A in Example 1 was omitted.
[0016]
Comparative Example 2
The same treatment as in Example 1 was performed except that the step of adding the amphoteric polymer coagulant B in Example 1 was omitted.
[0017]
Comparative Example 3
10 ml of 0.2% aqueous solution of amphoteric polymer flocculant B was added and stirred for 30 seconds.
[0018]
Comparative Example 4
Add 0.3 ml of 40% ferric chloride aqueous solution and stir for 30 seconds, then add 10 ml of 0.2% aqueous solution of amphoteric organic polymer flocculant B, stir for 30 seconds, then anionic organic polymer agglomeration 7 ml of 0.1% aqueous solution of Agent A was added and stirred.
[0019]
Table 2 shows the results of evaluating the floc aggregation state (floc diameter) and the ease of solid-liquid separation in Example 1-2 and Comparative Example 1-4.
[0020]
[Table 2]

Claims (1)

Add the flocculant to the organic sludge containing fats and oils, separate the agglomerated flocs, and then dehydrate it with a dehydrator. Add the first iron-based or aluminum-based acidic inorganic flocculant as the flocculant. And, an anionic organic polymer flocculant is added second, and an amphoteric organic polymer flocculant is added third, and the organic sludge dewatering method is characterized.